বগা বালিমাহী
বগা বালিমাহী, (, বৈজ্ঞানিক নাম-Motacilla alba) এটা সৰু আকাৰৰ বালিমাহী চৰাইৰ প্ৰজাতি৷ ই ঘাইকৈ ইউৰোপ, এছিয়া আৰু উত্তৰ আফ্ৰিকাত প্ৰজনন কৰে৷ বগা বালিমাহী পতংগভোজী৷ ইহঁতে প্ৰধানকৈ জলাশয় বা পানীৰ অন্যান্য উৎসৰ আশে পাশে চৰে৷

বিৱৰণ
The White Wagtail is a slender bird, 16.5–19 cm (6½–7½ in) in length (East Asian subspecies are longer, measuring up to 21 cm (8¼ in), with the characteristic long, constantly wagging tail of its genus. Its average weight is  and the maximum lifespan in the wild is ca. 12 years. The nominate subspecies Motacilla alba alba is basically grey above and white below, with a white face, black cap and black throat.
he call of the White Wagtail is a sharp chisick, slightly softer than  the version given by the Pied Wagtail. The song is a pleasant twittering, more regular in White than Pied, but with little territorial significance, since the male uses a series of contact calls to attract the female.

টেক্স'নমি
Nine or eleven subspecies are currently recognised. Information on the plumage differences and distribution of the subspecies of the White Wagtail is shown below.

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বিতৰণ

This species breeds throughout Eurasia up to latitudes 75°N, only being absent in the Arctic from areas where the July isotherm is less than 4 °C. It also breeds in the mountains of Morocco and western Alaska.

বাসস্থান
It occupies a wide range of habitats, but is absent from deserts.

আচৰণ
The most conspicuous habit of this species is a near-constant tail wagging, a trait that has given the species, and indeed the genus, its common name. In spite of the ubiquity of this behaviour, the reasons for it are poorly understood.

খাদ্য
The exact composition of the diet of White Wagtails varies by location, but terrestrial and aquatic insects and other small invertebrates form the major part of the diet. These range from beetles, dragonflies, small snails, spiders, worms, crustaceans, to maggots found in carcasses and, most importantly, flies in the order Diptera. Small fish fry have also been recorded in the diet.

প্ৰজনন

White Wagtails are monogamous and defend breeding territories. The breeding season for most is from April to August, with the season starting later further north. Both sexes are responsible for building the nest, with the male responsible for initiating the nest building and the female for finishing the process. The nest is set into a crevice or hole; traditionally in a bank next to a river or ditch, but the species has also adapted to nesting in walls, bridges and  buildings. One nest was found in the skull of a walrus. They species will nest in association with other animals, particularly where available the dams of beavers and also inside the nests of Golden Eagles. Around 3–8 eggs are laid, with the usual number being 4–6. Its eggs are cream-coloured, often with a faint bluish-green or turquoise tint, and heavily spotted with reddish brown; they measure, on average, 21×15 mm (0.83×0.59 inches). Both parents  incubate the eggs, although the female generally does so for longer and incubates at night. The eggs begin to hatch after 12 days (sometimes as late as 16 days). Both parents feed the chicks until they fledge at around 14 days, and the chicks are fed for another week after fledging.

স্থিতি
This species has a large range, with an estimated extent of more than 10 million km² (3.8 sq mi). The population size is unknown, but it is believed to be large, as the species is described as "common" in at least parts of its range. Population trends have not been quantified, but the species is not believed to approach the thresholds for the population decline criterion of the IUCN Red List (i.e. declining more than 30% in ten years or three generations). For these reasons, the species is evaluated as Least Concern. The population in Europe appears to be stable.

আলোকচিত্ৰৰ ভঁৰাল

তথ্যসুত্ৰ

বাহ্যিক সংযোগ

 Wagtail videos, photos & sounds on the Internet Bird Collection
 Norwegian Cyberbirding: Masked, Pied & White Wagtails photos . 
 Romani Rise: Pied Wagtail – the Gipsy Bird  Pied Wagtails in Welsh Romani culture
 Identification article with pictures (PDF) 
Ageing and sexing (PDF; 4.9 MB) by Javier Blasco-Zumeta & Gerd-Michael Heinze

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